Houllier stands by his decision to make eight alterations to his line-up for the fifth round tie which Villa lost 3-0. But he accepts he should have made the 900 travelling supporters aware that he intended to field a drastically different line-up to the one in action against Blackburn last weekend.
Houllier said: "I am sorry. I should have warned the fans beforehand. I made changes against Sheffield United and Blackburn in the cup in previous rounds and felt I had to again."
He added: "I thought we could beat City on the break. We put two very quick players on the wing, and the plan was Emile Heskey would drop deep. We went there to win but unfortunately the first goal killed our players right away."
Houllier felt his side still contained plenty of quality and experience to tackle City.
He said: "We went out not with a youth side. Gabby Agbonlahor was called up by Fabio Capello for the last England game. Emile Heskey has won 62 caps and played in the last World Cup. He was the centre forward here before Darren (Bent) came.
"In midfield you had three international players. Stiliyan Petrov is our captain. It was a debut for Michael Bradley but he has proven in training that he is getting there.
"Barry Bannan has been outstanding even at the beginning of the season when we were forced to push him into the first team and now he's an international player for Scotland. It was not a youth team."
Houllier is adamant that ensuring Barclays Premier League status for another campaign is the main priority at this juncture.
He said: "We wanted to do well in the cup. I am hurt myself. I don't think we played badly but I think we could have hurt them more from an offensive point of view. But at the moment, the priority is to get more results and progress in the league."
Source: PA
Source: PA